How can I display custom app data on my store's frontend?

Shopify Apps
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2

Two ways:

  1. Shopify App Blocks where your merchant(s) can bring in data from the app
    https://shopify.dev/themes/architecture/sections/app-blocks
  2. Or you could create metafields with your app that can be outputted by liquid in your theme
    https://shopify.dev/apps/data-extensions/metafields